EUEahtasham Ummamineahtasham.hashnode.dev·5d ago · 12 min readHow Does Instagram Check If a Username Is Taken Instantly? (Bloom Filters Explained)You're signing up for a new account. You type a username — john — and before your finger even leaves the keyboard, a little red ✗ appears: "Username already taken." You try john_dev_2025, and instantl00
EUEahtasham Ummamineahtasham.hashnode.dev·Apr 11 · 19 min readUnderstanding tempmail-checker — How It All WorksA deep-dive into the architecture, data structures, and algorithms behind tempmail-checker. Table of Contents The Problem The Naive Approach and Why It Falls Short Bloom Filters — The Core Innovat00
EUEahtasham Ummamineahtasham.hashnode.dev·Apr 9 · 3 min readThe 6-Digit Secret: How Authenticator Apps Verify OTP They Never StoreAuthenticator apps have become the backbone of modern account security. When you enable two-factor authentication (2FA), you likely rely on tools like Google Authenticator or Microsoft Authenticator. 00
EUEahtasham Ummamineahtasham.hashnode.dev·Apr 3 · 2 min readnpm vs npx: Same Family, Very Different JobsIf you’ve been writing JavaScript for more than 10 minutes, you’ve seen npm and npx everywhere. And at some point, you probably thought: “Why do we even have both? Isn’t one enough?” Fair question. 00
